1. Field of the Invention
The present invention relates to sealing devices for the rim space between the inner wall of a storage tank and the periphery of a floating cover therein. Specifically, the present invention relates to improvements in the mechanism to allow shoe segments of the sealing ring to overlap.
2. Prior Art
Bulk fluids such as petroleum and fuel products are usually stored in large cylindrical storage tanks. These are commonly designed with floating covers to minimize product losses to the atmosphere. A critical part of the floating cover is the sealing mechanism that is installed in the annular or rim space between the floating cover and the inner wall of the storage tank.
A rim space sealing device is disclosed in Applicant's and Assignee's patent (U.S. Pat. No. 5,036,995) entitled "Peripheral Seal for Floating Tank Cover" which is incorporated herein by reference. A series of shoes disposed around the periphery of the tank wall are frictionally engaged with the wall. Adjacent shoes are allowed to overlap a certain distance. As seen in FIG. 11 on sheet No. 4, the vertical movement of the overlapping shoe segments in relation to each other is limited by a series of retainer rods 82. The retainer rods are held in place by upper clips 58 having opposed legs that form a space for a clamping channel. The attachment point of the clamping channels at the joint must be outside the lapped area shown by arrow 38.
Typically, the sealing mechanism is assembled and installed on site in the field from components. The holes or openings for fasteners are also shop fabricated in advance. If the components are assembled with the laps of the shoes reversed the flexible shoes might possibly be caused to bind. This would limit the optimum expansion flexibility of the joint.
It is, therefore, a principal object and purpose of the present invention to provide a peripheral seal device wherein the overlapping shoe segments may be field assembled in one way only.
It is a further object and purpose of the present invention to provide a peripheral seal device wherein clips at one side edge are attached only to a single shoe so that the adjacent shoe is free to overlap without restriction.